dotcloud/docker

package containerd

import (
    "context"

    "github.com/containerd/containerd/content"
    containerdimages "github.com/containerd/containerd/images"
    cerrdefs "github.com/containerd/errdefs"
    ocispec "github.com/opencontainers/image-spec/specs-go/v1"
)

// walkPresentChildren is a simple wrapper for containerdimages.Walk with presentChildrenHandler.
// This is only a convenient helper to reduce boilerplate.
func (i *ImageService) walkPresentChildren(ctx context.Context, target ocispec.Descriptor, f func(context.Context, ocispec.Descriptor) error) error {
    return containerdimages.Walk(ctx, presentChildrenHandler(i.content, containerdimages.HandlerFunc(
        func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
            return nil, f(ctx, desc)
        })), target)
}

// presentChildrenHandler is a handler wrapper which traverses all children
// descriptors that are present in the store and calls specified handler.
func presentChildrenHandler(store content.Store, h containerdimages.HandlerFunc) containerdimages.HandlerFunc {
    return func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
        _, err := store.Info(ctx, desc.Digest)
        if err != nil {
            if cerrdefs.IsNotFound(err) {
                return nil, nil
            }
            return nil, err
        }

        children, err := h(ctx, desc)
        if err != nil {
            return nil, err
        }

        c, err := containerdimages.Children(ctx, store, desc)
        if err != nil {
            return nil, err
        }
        children = append(children, c...)

        return children, nil
    }
}